V3xar's 2nd soloution with the regedit merge worked
I've been plagued with this problem for months now, and before this the only solution was a "safe-mode" system restore. Every time I get an update from Microsoft, it changes the "Folder" registry values apparently, and makes it so that I cannot double click open any sub-folders. And sometimes it would just happen without the updates, I have the most current year and version of Norton 360 with current virus definitions...no virus detected at all. All I could do was bring up the drop down menu and manually open each folder. Now that I have this fix downloaded....if this problem ever happens again, I can re-fix it in a matter of seconds.
madmansam, I don't think you read the first post fully, this problem has nothing to do with mouse speed/clicking.